Re: [PATCH v2] xfs: Check for deallayed allocations before setting extsize

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Oct 10, 2024 at 12:06:17PM +0530, Ojaswin Mujoo wrote:
> Extsize is allowed to be set on files with no data in it. For this,
> we were checking if the files have extents but missed to check if
> delayed extents were present. This patch adds that check.
> 
> While we are at it, also refactor this check into a helper since
> its used in some other places as well like xfs_inactive() or
> xfs_ioctl_setattr_xflags()
> 
> **Without the patch (SUCCEEDS)**
> 
> $ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'
> 
> wrote 1024/1024 bytes at offset 0
> 1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
> 
> **With the patch (FAILS as expected)**
> 
> $ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'
> 
> wrote 1024/1024 bytes at offset 0
> 1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
> xfs_io: FS_IOC_FSSETXATTR testfile: Invalid argument
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
> ---
> 
> * Changes since v1 *
> 
>  - RVB by Christoph
>  - Added a helper to check if inode has data instead of
>    open coding.
> 	
> v1:
> https://lore.kernel.org/linux-xfs/Zv_cTc6cgxszKGy3@infradead.org/T/#mf949dafb2b2f63bea1f7c0ce5265a2527aaf22a9
> 
>  fs/xfs/xfs_inode.c | 2 +-
>  fs/xfs/xfs_inode.h | 5 +++++
>  fs/xfs/xfs_ioctl.c | 5 +++--
>  3 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index bcc277fc0a83..3d083a8fd8ed 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -1409,7 +1409,7 @@ xfs_inactive(
>  
>  	if (S_ISREG(VFS_I(ip)->i_mode) &&
>  	    (ip->i_disk_size != 0 || XFS_ISIZE(ip) != 0 ||
> -	     ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0))
> +	     xfs_inode_has_data(ip)))
>  		truncate = 1;
>  
>  	if (xfs_iflags_test(ip, XFS_IQUOTAUNCHECKED)) {
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 97ed912306fd..ae1ccf2a3c8b 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -292,6 +292,11 @@ static inline bool xfs_is_cow_inode(struct xfs_inode *ip)
>  	return xfs_is_reflink_inode(ip) || xfs_is_always_cow_inode(ip);
>  }
>  
> +static inline bool xfs_inode_has_data(struct xfs_inode *ip)

Can you please change this to "const struct xfs_inode *ip"?
This predicate function doesn't change @ip.

I might've called it xfs_inode_has_filedata fwiw, but the current name
is fine with me.

--D

> +{
> +	return (ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0);
> +}
> +
>  /*
>   * Check if an inode has any data in the COW fork.  This might be often false
>   * even for inodes with the reflink flag when there is no pending COW operation.
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index a20d426ef021..88b9c8cf0272 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -481,7 +481,7 @@ xfs_ioctl_setattr_xflags(
>  
>  	if (rtflag != XFS_IS_REALTIME_INODE(ip)) {
>  		/* Can't change realtime flag if any extents are allocated. */
> -		if (ip->i_df.if_nextents || ip->i_delayed_blks)
> +		if (xfs_inode_has_data(ip))
>  			return -EINVAL;
>  
>  		/*
> @@ -602,7 +602,8 @@ xfs_ioctl_setattr_check_extsize(
>  	if (!fa->fsx_valid)
>  		return 0;
>  
> -	if (S_ISREG(VFS_I(ip)->i_mode) && ip->i_df.if_nextents &&
> +	if (S_ISREG(VFS_I(ip)->i_mode) &&
> +	    xfs_inode_has_data(ip) &&
>  	    XFS_FSB_TO_B(mp, ip->i_extsize) != fa->fsx_extsize)
>  		return -EINVAL;
>  
> -- 
> 2.43.5
>